It is possible that the main title of the report Marfan Syndrome is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.
As Jenny points out, being able to lisp the alphabet song at age two has little to do with 'knowing' the alphabet. And, yes, most children learn the letters by sight and sound in kindergarten, although most are capable of learning this information sooner if diligently taught by parents or others.
What is the Alphabetic Principle? Most reading specialists agree that it's best to begin by introducing children to letters and sounds that are the least confusing. There are a number of different opinions on the best way to teach children to work with the alphabetic principle. Most people learn the alphabet before they learn how to read words.